MEASUREMENT OF MECHANICAL LOSSES IN THE COMBUSTION ENGINES

Transcription

1 Jurnal f KONES Pwertrain and Transprt, Vl. 17, N MEASUREMENT OF MECHANICAL LOSSES IN THE COMBUSTION ENGINES Ond ej Dráb, Rbert Vženílek, Stanislav Berun Technical University f Liberec, Department f Vehicles and Engines Studentská Street 2, Liberec, Czech Republic tel: , , fax: , ndrej.drab@tul.cz, rbert.vzenilek@tul.cz, stanislav.berun@tul.cz Abstract The develpment f a new cmbustin engines is cnnected with endeavur fr escalatin f the ttal efficiency. Escalatin f the ttal efficiency can be: minimizatin f the mechanical lsses in the cmbustin engines r minimizatin f the unsuitable equipment capacity f accessries. Nw research and develpment prgrams f a manufacturer f the cmbustin engines search effectual equipment and methd fr this escalatin f the ttal efficiency. The escalatin f the ttal efficiency is imprtant fr a minimizatin fuel cnsumptin and cnsequently fr lwer emissins. Turn f the cmbustin engines is used methd fr measurement f mechanical lsses very ften. The paper will shw chice f the measurement results n the testing bench. The Technical University f Liberec, Department f Vehicles and Engines, has develped a design f a testing bench which wuld enable the measuring mechanical lsses f the cmbustin engines fr different temperatures f cling water and engine lubricatin il. Each medium (lubricatin il and cling water) have wn circle with autmatic temperature regulatin. The testing bench has autmatic system fr change revlutin and autmatic system fr measurement: trque, revlutin, temperatures and pressures. The asynchrnus mtr (cmpany SIEI, type MA 133 K - 62 with pwer 28 kw/ /min) is used fr drive f cmbustin engine in the testing bench. Keywrds: cmbustin engine, measurement f mechanical lsses 1. Intrductin An increase f verall efficiency f engines by means f reducing mechanical lsses in the engine r by cutting dwn useless pwer inputs t grups f accessries is f very high interest nwadays. Therefre, research and develpment prgrams f engine manufacturers (and f the autmtive industry generally) fcus n lking fr effective measures increasing the verall efficiency f pistn cmbustin engines. An imprtant part f these effrts als cnsists in methds serving t ascertain mechanical lsses, with quantitative evaluatin f the effect f implemented mdificatins r even essential alteratins in the engine. One f ften emplyed methds f ascertaining mechanical lsses in the engine is induced revlutin f the engine n a testing rig with electric dynammeter. Such measuring f a cmplete engine can bring rather satisfactry results. A certain disadvantage f these measurings are the values f the lss trque, which are relatively lw with respect t nminal value f the mment f the pick-up n the dynammeter; cnsequently, the result f measuring is laden with a relatively higher degree f uncertainty. The mdern testing (brake) stands with autmated measuring (data cllectin, stabilisatin f temperatures bth f clant and lubricatin il) suppress the said disadvantage t a great part; nevertheless, mdern brake rigs are emplyed fr measuring mechanical lsses in the engine by induced revlutin nly as a cmpnent f mre extensive measurings n the engine. T emply a brake rig equipped with mdern testing and measuring equipment fr studying mechanical lsses (passive resistances) f the cmplete engine r f its structural assemblies nly is nt ecnmical; therefre, it is f advantage t realise such experimental research n separate testing stands.

2 O. Dráb, R. Vženílek, S. Berun 2. Testing bench fr measurement f mechanical lsses in the cmbustin engines As the basis f the testing statin fr measuring mechanical lsses in pistn cmbustin engine by induced revlutin there serves a regulating inductin mtr f the firm SIEI, type MA 133 K-62, with the utput 28 kw/6000 1/min. The trque during induced revlutin is measured by a shaft pick-up HBM f the type T20WN (100 Nm, 0.2%, /min), r by a pick-up HBM T5 (50 Nm, 0.1%, /min) bth pick-ups can be verladed statically t 200% f nminal value f Mt. Because f the required range f r. p.m., the basic cnfiguratin f the testing rig is equipped with the pick-up T20WN. Fig. 1. Testing bench fr measurement f mechanical lsses in the cmbustin engines In rder t guarantee reprducibility f measurings f trque lss by means f induced revlutin f pistn cmbustin engine, an acceptably lw variability f temperatures (verall warming-up f the engine, temperatures f clant and lubricatin il) must be prvided n the revlved engine. The testing stand is equipped with a system f exchangers (heaters, clers), cnnected t cling and lubricating systems f the revlved engine. The heating/cling f clant in the cling circuit as well as the heating/cling f lubricatin il in the circuit f engine lubricatin are regulated by cntrlled heating by means f electric heating elements and/r by cntrlled peratin f a fan n auxiliary cler. The peratin f the whle system fr temperature cntrl is ptimised step by step by means f PID regulatrs. 2. Measurement system The testing rig fr induced revlutin f the engine is cupled with a data lgger MGCplus (Httinger), allwing t recrd samples f data per secnd in the 8-channel versin f the amplifier. Each sample cmprehends the data frm the pick-up f the trque (Mt and revlutins n) and frm 13 temperature pick-ups (Pt 100 and thermcuples). The number f sensed temperatures can be increased accrding t measuring needs. Frm the effective values f the measured trque and r. p.m., the pwer lss is calculated. 64

3 Measurement f Mechanical Lsses in the Cmbustin Engines cmbustin engine circuit 1 circuit 2 circuit 3 engine sump water pump valve il pump heating spiral water cler water cler heating spiral water pump il cler water tank Fig. 2. Scheme f fluid circuits ventilatr The peratinal envirnment fr measuring passive resistances is generated by means f the SW CaMtan Easy. During measuring, n the PC mnitr there are displayed graphical values f measured temperatures and the time curses f Mt and n. The values f all measured quantities (Mt, n and temperatures) fr each measured regime are established by statistic data prcessing (as mean values f the data file in chsen time interval). The Fig. 3 shws a pht f the mnitr with displayed data f mnitred quantities. Circular indicatrs present the infrmatin f measured temperatures; in the centre f the mnitr, there is displayed the time curse f the measured trque Mt, and in the bttm f the mnitr, the time curse f mmentary r. p.m. (n the basis f data f this curse, it is pssible t determine the variability f angular velcity in the lcatin f the trque pick-up). 3. Cntrl system T prvide fr autmatic cntrl f r. p.m. f the regulated inductin mtr (r frequency cnverter), an applicatin fr the required change f r. p.m. regime has been generated in the cmputer. At the same time, this applicatin gverns the cllectin f samples in the respective time segment, which cntributes t repeatability f measuring. 4. Results f measurement Fr the cmparisn f curses f the trque lss, tw temperature regimes have been chsen. As the first temperature regime, 35 C have been chsen fr bth media (lubricatin il and 65

4 O. Dráb, R. Vženílek, S. Berun clant/water) fr cld engine, and as the secnd ne, 90 C fr bth media (lubricatin il and clant/water) fr warm engine. The regime f r. p.m. change is shwn in the Fig. 4. The cmbustin engine has been revlved in the range f r. p.m. The step f a change f r. p.m. has been chsen t amunt t 250 r. p.m. Engine speed [1/min] Pr b h testu Time [s] Fig. 4. Run f the test Relative trque f lsses [% Temperature 35 C Engine speed [1/min] Fig. 5. Relative trque f lsses fr cld cmbustin engine 66

5 Measurement f Mechanical Lsses in the Cmbustin Engines Relative trque f lsses [% Temperature 90 C Engine speed [1/min] Fig. 6. Relative trque f lsses fr ht cmbustin engine The diagrams shw relative values f the trque lss. The value at the highest measured velcity r. p.m. is cnsidered in the diagrams as 100 %, and ther values f measured trque lss have been related t this value. The diagrams allw nticing the tendency f the measured trque lss t increase with increasing r. p.m. f the revlved cmbustin engine. With a cld cmbustin engine, the measured trque lss fr the highest measured r. p.m. (5.500 r. p.m.) is 1.82 time higher than at the lwest measured velcity (1.500 r. p.m.). With a warmed-up cmbustin engine (warm engine 90 C), the difference f the measured trque lss between r. p.m. and r. p.m. increases t as much as 2.13 multiple. 5.Cnclusin The verifying measurings f mechanical lsses f a pistn cmbustin engine by means f induced revlutin n the testing rig have prved full functinality f the testing rig, bth cncerning the requirement t measure the trque lss with high precisin and repeatability, and maintaining stable temperature cnditins during measuring by means f regulatin f temperatures f clant and lubricatin il. The results f measurings carried ut until nw shw that by means f the testing statin fr measuring mechanical lsses in pistn cmbustin engines by induced revlutin it is als pssible t study such characteristics f the engine that ther (calculatin r experimental) prcedures d nt shw. Acknwledgments This paper was develped thanks t the cntributin f the Ministry f Educatin, Yuth and Physical Educatin as Prject 1M0568 Jsef Bžek Research Centre II. Tent p ísp vek vznikl za p isp ní Ministerstva šklství mládeže a t lvýchvy jak prjekt 1M0568 Výzkumné centrum spalvacích mtr a autmbil Jsefa Bžka II. References [1] Vženílek, R., Berun, S., Zkušební stanice pr m ení mechanických ztrát v mtru, Funk ní vzrek, Technická univerzita v Liberci,